'Synthesis and properties of amorphous nanosilica from rice husk and its composites

Highlights: • Amorphous nanosilica isprepared from rice husk (agriculture waste) by employing cost-effective and environment-friendly method. • TheXRD analysis reveals the small crystallite size. The SEM, TEM and SAED patterns support the XRD pattern analysis. • Nanosilica exhibits excellent optical properties in the visible range and band gap found to be 3.35 eV, which is slightly higher than its bulk value. • The amorphous nanosilica is found to be a diamagnetic material. The magnetic polymers are found to be ferrimagnetic nature. • The magnetic hysteresis loops of amorphous nanosilica/Ferrite/PVDF composites reveal that these materials can be used as polymer magnet. Amorphous nanosilica (SiO₂) was prepared from rice husk by a cost-effective and environment-friendly method. Magnetic nanocomposite has been prepared by using injection molding equipment from amorphous nanosilica, ferrites, and PVDF. The XRD pattern analysis reveals the amorphous nature of the silica. The particle size of SiO₂ was observed from the SEM and TEM analysis and found to be very small, which suggests the formation of amorphous nanosilica from the rice husk. FTIR spectra show the absorption peaks of SiOiSi (silanol) functional group. The photoluminescence spectrum reveals the broad excitation of radiation in the visible region. A characteristics peak in UV–Vis absorption spectra occurs at 365 nm, and the optical band gap was found to be 3.35 eV. Magnetic study shows the diamagnetic nature of amorphous nanosilica. The nanocomposite of amorphous nano silica-Ferrite-PVDF exhibits ferromagnetic nature due to the presence of ferrite in the nanocomposite. The magnetic hysteresis loop of nanocomposite reveals that the materials can be used as polymer magnet. The physical properties of amorphous nansilica and its composite with PVDF and ferrite have been explored in the present article. The present study may help to use prepared nanosilica materials in technological applications.